Voltage control device



Oct- 31. 1967 v YAsuNosUKE 'roRn 3350,630

VOLTAGE CONTROL DEVICE Filed Dec. v, 1964 is-sheets sheet 1l f FIG. 2

LHc1c2cac4cs OO O O v OO VO Q Oct. 31, 1967 YA'suNosuKE ToRn 3,350,630

' I voLTAGE coNT RvoL DEVICE l Filed Dec. 7,` 1964 3 Sheets-Sheet 2 F/G. a

IPG -6/7 Oct. 31, 1967 'YASUNOSUKE TORII VOLTAGE CONTROL DEVI CE Filed Dec.

3 Sheets-She e'rl 3 FIG. 5?

HHHI o s Zitt FIG. 6

United States Patent O 3,350,630 V VOLTAGE CONTROL DEVICE Yasunosuke Torii, Musashino-shi, Tokyo, Japan, assignor to Tokyo Shibaura Electric Co., Ltd., Kawasaki-sbi, Japan, a corporation of Japan Filed Dec. 7, 1964, Ser. No. 416,245 2 Claims. (Cl. 3Z3-43.5)

This invention relates to a Voltage control device and more particularly to a device for supplying variable alternating current Voltage to a load and is especially useful to supply variable Voltage to traction motors of an AC electric car through a car mounted transformer provided with a plurality of Voltage regulating taps.

, It is an object of this invention to provide an improved Voltage vcontrol device which is simple in construction and light in weight.

A further object of this invention is to provide a Voltage control device for AC electric cars which can provide a larger number of notches with less number of taps and contactors than conventional speed control devices.

For a more. complete understanding of this invention reference may be had to the following detailed explanation in connection with the accompanying drawings in which: i

FIG. 1 shows a connection diagram of a typical main circuit of a conventional control device for an alternating current electric car;

FIG. 2 shows a-sequence table of tap-Changing operation of the control device shown in FIG. 1;

'FIG. 3 shows a connection diagram of the main circuit of a control device embodying this invention for an alternating current electric car;

FIG. 4 shows a sequence table of tap-changing operation of the control device shown in FIG. 3; and v FIGS. 5 and 6 show -portions of the main circuits of another embodiment of this invention. V

Referring first to FIG. 1 of the accompanying drawing illustrating a connection diagram of a Conventional control device there is Imounted on an electric car a transformer 1 having a primary winding P) connected between a pantograph PG and the earth, and a secondary winding S provided With say 6 taps TI to TG inclusive over` about one half ofits length. Across the secondary winding S is connected a slidable resistor RH having high and low Voltage terminals H and L. A sliding arm 2 of the slidable resistor RH is connected to one terminal of a load 3, or traction motors in this embodiment. As shown in FIG. l, taps TI to TG are provided on the lower half of the secondary Winding adjacent its low Voltage terminal, add numbered taps TI, T2 and TI, being connected to one bus bar 4 via contactors CI, C3 and C5, respectively, while the even numbered taps T2, T4 and TG to the other bus bar 5 via contactors C2, C4 and C6, respectively. A v'current balancing--reactor 6 is connected across bus bars 4 and 5 With itsy mid side of the load 3; f

As shown in the notchsequence table, shown in FIG. 2, at the first notch the sliding arm 2 of the resistor RH is positioned on the L side and the contactors CI and C2 are closed. Thus the bus bars 4 and 5 are connected to the taps TI and T2 so that a Voltage intermediate these taps will be supplied to the load 3. At the second tap,

the contactor CI is opened while contactors C2 and, C2 are closed so that a Voltage intermediate taps T2 and Ta will be supplied to the load. In this manner the Voltage applied to the load will be gradually increasedl until the fifth notch is reached at which time a Voltage intermediate the taps T5 and TG will be supplied to the load 3. It is to be understood that, under this condition, a Voltage corresponding to about one half of thevoltage induced in the secondary winding S will be supplied to point 7 connected to the opposite' ICC the load. At the sixth notch the sliding arm 2 is transferred from L to H side but this will result in no change in the load Voltage. At successive stages from seventh to tenth notches inclusive the respective contactors will be operated in an order reverse to that described above to successively add intermediate tap voltages to one half of the secondary Voltage so that at the final or tenth notch full secondary Voltage will be supplied to the load-3.

'While with the above described prior arrangement the number of'taps and hence the number of contactors can be considerably reduced since these taps are required to be provided for only one half of the secondary winding to gradually increase the load Voltage from minimum to the full secondary Voltage, there are such defects that it requires to provide a resistor RH which normally consumes substantial amount of electric power and also requires to use a mechanism to transfer between L and H side terminals of the resistor RH. Moreover, when it is desired to increase the number of notches, the number of taps and contactors must also be increased, thus `resulting in 'a complicated construction of the transfonner winding.

Thus, it is the feature of this invention to provide a novel Voltage control system, which is especially suitablev for use in electric cars and can provide a larger number of notches with relatively small number of taps and contactors. a

An illustrative example of this invention as applied to speed control of an alternating current electric train Will now be described by referring to FIG. 3, wherein the same or corresponding parts are designated by Vthe same reference Characters as inYFIG. 1. In this embodiment the 'transformer 1 is provided with three secondary windings SO, SI and S2. Among these, the winding SI, alone is pro- Vided with five Voltage regulating taps TI to T5 inclusive for example and thus termed as the Voltage regulating winding. It is. designed that the secondary winding SI will induce a Voltage which is equal to the sum of the Voltage` of the winding SI, and the tap Voltage and that the secondary'winding S2 a higher Voltage which is equal to the sum of the Voltages of windings SI and SI,v and lthe tap Voltage of the winding SO. The odd numbered taps TI, T3 and T5 of the Voltage regulating winding So are connected to a bus bar 4 respectively through contactors CI, C3 and-C5 while the even numbered taps T2 and VT4 Vto a bus bar 5 through' contactors C2 and C4 respectively.

A balancing reactor 6 is connected across bus bars 4 and 5 with its mid point connected to one terminal of theV load 3. The upper terminal of the winding SI is connected to the bus bar 5 through a contactor C6 while the upper terminal of the winding- S2 is also connected to the same bus bar through a contactor C7. 'The lower terminals of the windings SI and SI, are connected to the other or grounded terminal of the loadl 3 through contactors C9 and C8, respectively, while the lower terminal of the winding S2 is direct'ly connected to said grounded terminal. The junction between the lower terminal of the Voltage regulating winding. So and the contactor C2 is connected to the upper terminal of the winding SI throu-gh a contactor CII, and also to the upper terminal of the Winding S2 through a contactor CII. The lower terminal of the Wnding SI is connected to the upper terminal of the winding S2 through a contactor CI2.

With reference to the notch sequence table of the above described control device, shown in FIG. 4, it will be noted that at the first notch, contactors CI and C8 are closed to apply the Voltage appearing at the first tap TI of the regulating winding So to the load 3 through the bus bar 4. At the second notch the contactor C2 will also be closed to apply a Voltage intermediate the taps TI and T2 to the load through bus bars 4, 5 and, the reactor 6. At the third notch the contactor CI will be opened and instead the contactor C3 closed to apply a Voltage applied to the load will be increased gradually. Upon reaching the sixth notch, the regulating windings So and Sl will be connected in parallel with respect to the load through the reactor 6 by the closure of contactors C5, C8, C9 and C6 whereby to apply to the load a Voltage intermediate the Voltage of the winding Sl and the Voltage of the highest tap T5 of the winding SO.

At the seventh notch contactors C5 and C8 will be opened and instead contactors C1 and Cm closed. As a result the upper terminal of the winding Sl will be connected to the bus bar 4 in series with the tap T1 of the resulting winding So thus applying to the lload a Voltage which is equal to the sum of the Voltage of the Winding Sl and the Voltage of the tap TI of the winding So. Thereafter the contactor C6 will be opened and the same sequence of Voltage control as has been previously described in connection with the notches 1 to 5 is repeated to further gradually increase the load Voltage. At the twelfth notch contactors C5, C9, Cm and C7 will be closed to connect a series combination comprising the windings So and Sl in parallel with the Winding SZ through the reactor 6 so that the Voltage supplied to the load will be increased by the tap Voltage of the regulator winding So and the sum of the voltages of the windings SO and Sl. Upon reaching the thirteenth notch the contactor C9 will be opened while contactors C1' C7 and Cu closed to connect the upper terminal of the winding Sz to the bus bar 5 and also to connect the series combination comprising the winding SZ and the tap T1 of the* Winding So to the bus bar 4 to further increase the load Voltage. Thereafter the contactors C1 to C5 inclusive will be sequentially closed to gradually increase the load Voltage by successively adding a Voltage intermediate two adjacent taps to the Voltage of the winding S2 until the eighteenth notch is reached at which time the contactors C5 land Cu will be closed. In order to further increase the load Voltage to provide the highest Voltage contactors 012 and Cm are closed to connect in series all of the Voltage regulating windings SZ, Sl and SO.

FIG. 5 shows a connection diagram of a modified embodiment of this invention wherein in addition to the regulating winding So with taps, three Voltage regulating windings Sl, SZ and Sa without tap are provided to increase the number of Voltage regulating notches. In still further modification shown in FIG. 6 the number of Voltage regulating notches is still further increased by pro- Viding four Voltage regulating windings Sl, S, S3 and S4 Without tap.

In the above arrangements embodying the principle of this invention if it is assumed that the number of Voltage regulating windings Without tap is equal to M and that the number of taps of the Voltage regulating winding is equal to N, the number of contactors will be expressed by the following equation:

the number of lead wires and the number of notches ZM x N -t-ZM-v 1 By the arrangement shown in FIG. 3, the number of the notches can be made to be equal to 23 with five sections of the regul-ating windings So, ten lead wires and twelve contactors, and by the arrangement shown in FIG. 4, the number of notches can be increased to 63 'with seven sections of the regulating windings SU, 15 lead wires and 19 contactors whereas the number of the notches may be greatly increased to 169 with 9 Sections of the regulating winding SO, 18 lead wires and 27 contactors.

Thus it will he seen that this invention provides considerably a large number of notches with relatively a small number of transformer taps and contactors whereby to simplify the construction of the transformer-,and reduce the number of parts requiring frequent repair and replacement.

While the embodiments of the invention as herein disclosed constitute preferred forms it is evident that other forms might be adapted. Thus, the control devices may be advantageously used in many applications where an alternating current Voltage supplied to a load should be varied over a wide range.

What is claimed is:

1. A Voltage control device comprising a source of alternating current, a load, a transformer connected between said source and said load,vsaid transformer having a primary winding connected across said source of alternating current and a plurality of secondary windings, the first secondary winding being a regulating winding producing a Voltage E and provided with a plurality of taps, the Voltage between taps being E', the second secondary winding providing a Voltage E +E', the third secondary winding producing a Voltage 2(E+E'), and nth secondary winding producing a Voltage 2n 2(E+E'), a first group of contactors each associated with the respective one of said taps of said regulating windings, a second group of contactors connected between the high Voltage side of each of the secondary windings and the low Voltage side of the other of said secondary windings, means to operate said first and second groups of contactors such that the Voltage supplied to said load is gradually increased in the first step, by said regulating winding, in the second step by serially connecting said regulating winding and said second secondary winding, in the third step by connecting in series said regulating winding with said third secondary winding, in the fourth step by connecting in series said first, second and third secondary windings, and in the nth step by connecting in series all of said secondary windings.

2. The Volt-age control device according to claim 1 wherein a reactor is provided with its mid-point connected to one terminal of said load and its opposite terminals connected to one of a pair of bus bars and alternate taps of said regulating winding are connected to different one of said bus bars through associated contactors.

References Cited UNITED STATES PATENTS Re. 17,230 3/1929 Travers 323-435 1,746,675 2/1930 Peterson 323-48 JOHN F. coUcH, Primal-y Examiner. f'

W, E- RAY, Assistant Examiner, 

1. A VOLTAGE CONTROL DEVICE COMPRISING A SOURCE OF ALTERNATING CURRENT, A LOAD, A TRANSFORMER CONNECTED BETWEEN SAID SOURCE AND SAID LOAD, SAID TRANSFORMER HAVING A PRIMARY WINDING CONNECTED ACROSS SAID SOURCE OF ALTERNATING CURRENT AND A PLURALITY OF SECONDARY WINDINGS, THE FIRST SECONDARY WINDING BEING A REGULATING WINDING PRODUCING A VOLTAGE E AND PROVIDED WITH A PLURALITY OF TAPS, THE VOLTAGE BETWEEN TAPS BEING E'', THE SECOND SECONDARY WINDING PROVIDING A VOLTAGE E+E'', THE THIRD SECONDARY WINDING PRODUCING A VOLTAGE 2(E+E''), AND NTH SECONDARY WINDING PRODUCING A VOLTAGE 2N-2(E+E''), A FIRST GROUP OF CONTACTORS EACH ASSOCIATED WITH THE RESPECTIVE ONE OF SAID TAPS OF SAID REGULATING WINDINGS, A SECOND GROUP OF CONTACTORS CONNECTED BETWEEN THE HIGH VOLTAGE SIDE OF EACH OF THE SECONDARY WINDINGS AND THE LOW VOLTAGE SIDE OF THE OTHER OF SAID SECONDARY WINDINGS, MEANS TO OPERATE SAID FIRST 